QUICK ANSWERStart with the tool that matches your immediate input.
Open ULID Generator first when its stated purpose matches the result you need now. Use User Agent Parser only when it solves a separate next task.
This guide is for developers, analysts, testers, and technical writers. Start with ULID Generator when your immediate task is to use the ULID Generator to inspect, transform, validate, or generate developer data locally in your browser. Move to User Agent Parser only when you also need to use the User Agent Parser to inspect, transform, validate, or generate developer data locally in your browser.
The goal is not to run two tools automatically. It is to finish the first narrow task, inspect its result, and then decide whether User Agent Parser solves a genuinely different next step.
Both tools sit in Developer & Data, but they handle different inputs or outcomes. Keeping those roles separate reduces repeated work and makes verification easier.